Universal rectangular wire coating die



R. W. MUNGALL UNIVERSAL RECTANGULAR WIRE COATING DIE April 18, 1944.

Filed May 20, 1943 2 Sheets-Sheet 1 Inventor": Robevt, W Mun gal I, 444414441 Hls Abtprney.

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April 18, 1944. R. w. MUNGALL UNIVERSAL RECTANGULAR WIRE COATING DIE 2 Sheets-Sheet 2 Filed May 20, 1943 Inventor. Robert, WMungal l, by )e a JMZ His Attorrfiey Patenteil Apr. 18, 1944 UNIVERSAL RECTANGULAR WIRE COATING DIE Robert W. Mnngall, Schenectady, N. 2., assignor Company, a corporation to General Electric v of New York Application. May 20, 1943, Serial No. 487,789

6 Claims.

This invention relates to apparatus for coating elongated articles, such as wire and the like, of rectangular cross section with liquid coating compositions, for example, with enamels. varnishes, lacquers, etc. The invention is especially concerned with a universal floating and self-centering applicator hereinafter referred to as a die, by the use of which wires or other elongated articles of any rectangular, including square, cross section (hereinafter referred to as rectangular wire), may be effectively and economically coated with viscous liquid coating compositions. The latter may include viscous solutions of resinous compositions obtained by condensing an aldehyde, such as formaldehyde, with the hydrolysis product of a polyvinyl ester such as a polyvinyl acetate.

The cross-sectional area of commercially available rectangular wire, including ribbon wire, is not always uniform along its entire length. Because of this fact, it has been found necessary in the coating of rectangular wire to use dies adapted to follow variations in the size and shape of the wire in order that a uniform coating of enamel may be applied to the surfaces of the wire irrespective of any changes in the cross-sectional area thereof.

An object of the present invention is to provide an improved, expansible, self-centering die for use in coating commercially available rectangular wire.

A further object of the invention is to provide a compact die which can be readily assembled about a wire to be coated.

Another object of the invention is to provide, in an expansible wire coating die, means for independently adjusting the pressure of a plurality of the wire-contacting die members on the wire.

A further object of the invention is to provide an adjustable. self-centering, expansible rectangular wire coating die capable of accommodating wires of various shapes and sizes including wires of extremely small cross section. Further objects of the invention will become apparent from the following detailed description of the invention when considered in connection with the accompanying drawings wherein Fig. l is a view partly in elevation and partly in section showing somewhat schematically coating apparatus embodying the invention;' Fig. 2 is, a perspective view of one form of die embodying the invention; Fig. 3 is a top view partially in section of portions of the die shown in Fig. 2; Fig. 4 is a perspective view of the partially disassembled die; and Fig. 5 is" an exploded view of the die prior to assembly.

The manner in which the invention may be applied to conventional wire coating apparatus of the vertical type is schematically illustrated in Fig 1. As shown in this figure a rectangular wire L is drawn from a pay-oi! reel 2 and under a guide sheave 3 immersed in liquid coating material 4 contained in a container or trough 5. The numeral 6 generally designates the die of the present invention. Specific details of the die are shown in Figs. 2, 3, 4, and 5. The die is shown in operative relationship with the container 5. Supporting structure for the die includes a pair of spaced parallel fingers 1 proiecting beneath the floating die with a second set of parallel fingers 8 of equal length above the die which act as stops to prevent the die from traveling upwardly with the wire.

The wire with a. uniform layer of coating composition of the desired thickness thereon is passed upwardly from the die through a drying or baking oven 9 provided with electric heating units 10 supported within the insulated oven walls I I. It will be understood that any suitable design of baking oven may be employed and that such oven may be heated with gaseous combustionproducts or by any other suitable means instead of the electric heating elements shown. The baked wire with its heat-hardened insulating coating thereon is passed over a drivin sheave l2 and is either recirculated through the coating material, additional dies and the oven to receive additional layers of baked coating material or is passed over pulley i3 to a take-up reel (not shown).

The die of the present invention which is particularly adapted for use in a vertical wire coating apparatus comprises a rigid rectangular frame having an aperture therein through which the wire to be coated passes and a. plurality of slidable wire-engaging die members mounted in recesses provided in the walls of they frame defining the aperture. The wire-engaging ends of these die members extend into the aperture in a plane perpendicular to the line of travel of the wire and cooperate to form a rectangular-shaped die opening to receive the wire. Each of the die members is provided with means for biasing it towards the center of the die so that when the die is not mounted about a wire the wire-contacting ends of the oppositely located die members contact one another. By this arrangement, the die members can be moved against their biasing means to form a rectanguiar opening accommodating a rectangular wire of any shape or size up to the dimensions of the aperture in the die frame.

The detailed structure of a die incorporating the invention will be best understood by reference to Figs. 2 to 5 of the drawings. The die illustrated in the drawings includes a'two-part rigid frame made up of a generally U-shaped member I4 and a cooperating member I! closing the open end of the U and forming one side of the frame. The extending end portions l6 and ll of the U- shaped member are of reduced cross section and are adapted to fit into recesses provided at the ends of member II which is held inoperative relationship of the U-shaped member by means of pins It and I! extending through the ends of member I! and the reduced end portions l8 and II of the U-shaped member. Member I is provided with a top plate 2| suitably secured thereto, as by means of screws 22 and 22', and having approximately the same general configuration as member I l. Member I! is provided with a similar fiat top plate 23 having the same shape as member II and secured thereto by means of screws 2|. When assembled, members I4 and I! with their top plates 20 and 23 cooperate to definea vertical aperture, shown as being of sugstantiaily rectangular cross section, through which the wire to be coated passes. The crosssectional area of the aperture is such as to receive the largestwire width which the die is to be used.

Actual control of the thickness of the layer of enamel applied to the wire is obtained by means of a plurality of die members 24, 25, 28, and 21 (Fig. 5). Member I! and each side of the U- shaped member II are slotted as indicated by numerals 28, 29, 3., and Ii so that the die members can be slidably mounted in the rectangular recesses defined by the walls of th slots, top

plates 20 or 23, and side plates 82, 32, 34, and 35 suitably secured as by means of screws to the outside walls of members It and 15.

As is shown more particularly in Figs. 4 and 5, two pairs of die members are provided. All of the die members are adapted to move in the same horizontal plane. Die members 24 and 28, which are shown as being of identical design, are U- ing arms 28 and 39 of rectangular cross section extending into the vertical aperture in the die frame between the extending arms of the respective U-shaped die members 24 and 28.

Means for forcing the die members of each pair toward each other are provided in the form of compression springs ll, l2,'and I! mounted behind the respective die members with one end of each spring inserted in a circular recess in the back of each of the die members and the other end inserted in the recesses in each of the set screws 44, l5, l8, and I1 screwed into threaded apertures in side plates 32, 33, 24 and 25. By this arrangement screws 44, ll, 46 and 41 may be used to vary and to adjust the spring pressure on the die members and thereby control the pressure of the die members on the surfaces of wire I. It is obvious that only one member of each pair of die members need be so biased to control the die pressure on the wire and to permit expansion and I contraction of the wire opening to pass any irregularities in the wire. However, the arrangement described wherein the spring pressure on each die member may be independently adjusted is more flexible in that the die may also be centered about the wire by suitable adjustment of the spring pressure on opposite die, members.

As a means for controlling the thickness of the enamel coating applied to th wire, the wire engaging ends of arms 38 and 39 of die members and 21 and at least the lower arms 36 and 21 of die members 24 and 20 are provided with a series of vertical ridges 38', 21', ll and I9 as shown in Figs. 3, 4 and 5 between which the proper amount of enamel is drawn by the upwardly moving wire. The height and number of these ridges will determine, for a coating composition of any given viscosity, the amount of coating material applied to the wire.

The excess enamel which is carried to the die by the vertically moving wire and is removed therefrom by the die members either flows back down the wire or collects within the space defined by the U-shaped die members and the wire engaging arms of the remaining die members and is discharged therefrom through holes ll and 4! in the bottom arms of the U-shaped die members and similar overlapping holes 50 and Ii in the bottoms of grooves 28 and 30. Similar enamel return passageways I2 and 53 are provided beneath die members 25 and 21. To prevent these latter die members from completel sealing passageways I2 and 3, a horizontal slot, such as indicated by numeral 54, is provided in the bottom of' that portion of each of the die members 25 and 21 which fits into grooves 28 and 30.

tion, the die members of each pair are biased t0-' wards each other and towards the center of the die by the compression springs with the members of one pair adapted to move in a direction perpendicular to the movement of the members of the other pair. When the die is not in use each of the die members is held in its respective recess 7 against the action of the biasing means by contact of its wire'engaging arm or arms with the wire engaging arm or arms of the opposite die member. In this position, the die opening is closed, 1. e., is of substantially zero dimensions in each direction. When the two parts of the dieframe are disassembled b removing pins II and ll, die members 2| and 26 continue to hold each other in position within the recesses while the die member 2!, the wire enga ing arm of which is enclosed by the adjacent ends of the members closing the recess in which die member 21 is mounted serves to retain that member within its recess "when the die frame is disassembled.

Either of two methods of mounting the die about a wire to be coated may be employed with the choice of methods depending upon whether or not the wire has already been threaded through the coating apparatus shown in Fig. 1. I! it has not, the end or wire may be inserted into the rectangular opening obtained by moving the die members against the action or their biasing means while the die is completely assembled. Preferably the wire is first threaded through the remainin parts' 01' the coating apparatus and the die or dies are then assembled about the wire. This is done by separating the die into its two major 7 parts as shown in Fig. 4, inserting the wire in proper coating position between die members 24 and 26 and thereafter reconnecting the two parts of the die which are then held in operative position about the' wire by means of pins i8 and It. If these operations have not been carried out with the die resting on supporting fingers I, the die with the wire inserted therein is swung into the space between fingers 1 and stops 8i As the wire is drawn through the coating apparatus, the die may be carried upwardly into contact with stops 8 where it is free to move or float, within certain limits, with any swaying movement of the wire passing through its central aperture and to center itself about the wire under the combined action 01' the various biasing springs. Undue or excessive movement of the die in the horizontal plane due to any unusual swayin or whipping or the wire is prevented by contact of the upturned flanges 58 and 59 with stops 8.

The spring pressure on the various die members is ordinarily adjusted by means of the adjusting screws, first. to obtain a substantial centering of any particular wire within the aperture in the die frame, and secondly, to obtain the proper pressure of the die members on the wire. This pressure is preferably just suflicieni to maintain a positive wiping action of the die members as the wire passes through the die. This amount of pressure on the wire will ordinarily exert a slight lifting action on the die so that it is lifted by the moving wire into contact with stops, where it will be free to follow the swaying action of the wire being coated. Freedom of movement of the die and die member is further facilitated by the lubricating action of the coating composition which collects within the die and on supports 5.

While I have shown a particular embodiment of my invention, I do not desire my invention to be limited to the particular construction shown and described, and I intend in the appended claims to cover all modifications within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An expanslble rectangular wire coating die comprising a rigid frame having walls definin a substantially rectangular aperture, a movable die member alidably mounted in a recess provided in each of said walls with the ends of said die member extending into said aperture and cooperating to define an opening for the wire to be coated, two of said die members being oppositely disposed and substantially U-shaped with the ends of the arms thereof forming wire engaging surfaces, the remaining oppositely disposed die members being provided with wire engaging arms extending into the aperture formed by the arms of the U-shaped die members, and means for biasing opposite die members towards each other.

2. A sell-centering expanslble rectangular wire coating die comprising a rigid frame havinga substantially rectangular aperture therethrough, the walls defining said aperture being provided with oppositely located recesses to receive movable .die members, die members slidably mounted in each of saidrecesses, the die members in one pair of oppositely located recesses being recessed to provide therein an aperture extending perpendicular to the aperture in said frame, a portion 01' each 01' the die members in each of the other pair of oppositely located recesses extending into the apertures formed by the die members of the first mentioned pair of oppositely disposed recesses and cooperating with said die members to form a die opening adapted to receive a wire to be coated, and spring means interposed between said frame and at least one die member of each pair to force the die members of each pair toward each other.

3. A self-centering expanslble rectangular wire coating die comprising a pair of die members of rectangular cross section. means for mounting said die members in opposed relation for relative movement in a direction perpendicular to the plane of said cross section, a second pair of opposed die members, means mounting I saidsecond pair of die members for movement in the plane of movement of said first mentioned die members and in a direction perpendicular to the movement of said first mentioned die members, said second pair of die members being provided with U-shaped recesses of such dimensions that the walls defining the recesses meet when the second pair of die members are moved toward each other to enclose the adjacent ends of said first mentioned die members, and means for biasing the die members of each pair toward each other to provide a die opening of rectangular cross section which increases in size in each direction as said die members are moved against the action of said biasing means.

4. A self-centering expanslble rectangular wire coating die comprising a pair of die members, means for mounting said die members in opposed relation within a rigid frame for relative movement in a direction perpendicular to the plane of said cross section, a second pair of oppo ed die members, means mounting said sec ond pair of die members within said frame for movement in a direction perpendicular to the movement of said first mentioned die members, said second pair of die members being provided with U-shaped recesses of such dimensions that the walls defining the recesses meet when the second pair of die members are moved toward each other to enclose the adjacent ends of said first mentioned die members, and means for biasing the die members of each pair toward each other to provide a die opening of rectangular cross section which increases in size in each direction as said die members are moved against the action of said biasing means.

5. An expanslble, self-centering die for use I in coating wire of substantially rectangular cross section, said die comprising a rigid rectangular frame, the walls of which define a rectangular shaped aperture, one side of said frame being detachably joined to the remaining portions thereof, a recess in each of the four walls defining said aperture with the recesses in opposite walls being oppositely disposed, a substantially U-shaped die member slidably mounted in each of one pair of oppositely disposed recesses with the arms of said members extending into said aperture, said U-shaped members being spring biased towards each other, a die member slidabiy mounted in each of the remaining pair of oppositely disposed recesses and spring biased toward the opposite die member, each of said last mentioned die members having an 'arm extending into said aperture between the arms of each of said U-shaped die members, the arms of all of said die members cooperating to form a die opening of rectangular .cross section which increases in size in each direction as the oppositely disposed die members are moved apart.

6. An expansible, self-centering die for use in coating wire of substantially rectangular cross section, said die comprising a rigid rectangular frame one side of which is detachabiy joined to the remaining portions of said frame. a substantially rectangular shaped aperture in said frame, a recess in each of the four walls defining said aperture, the recesses in opposlte walls being oppositely disposed and perpendicular to the plane of the aperture in said frame, a substantially U-shaped die member slidably mounted in each of one pair of oppositely disposed recesses with the arms oi! said U- shaped members extending into said aperture, said U-shaped members being spring biased towards each other, a die member slidably mounted in each or the remaining pair of oppositely 10 disposed recesses and spring biased toward the opposite die member, each of said last mentioned die members having an arm extending into said aperture between the arms of each of said U-shaped die members, the arms of all of 15 said die members cooperating to form a die opening of rectangular cross-section which increases in size from substantially zero dimension in each direction as the oppositely disposed die members are moved apart.

ROBERT W. MUNGAIL. 

